i just bought a music essentials kit from verizon store, i am completely legit. and when i go to sync music in my u740 it says connect failure check cable. its plugged in trust me. what gives everything is installed as well.
There may be a problem w/ your phone, take it in to your Verizon store and have them check it. You may want to reinstall your software first and make sure you d/l the phone drivers too.